一个英语短文的迷惑-----高手帮忙

这种情况我也没见过,我根据我的理解来给你解释一下吧.
of its day如果是这么用,那么前面的主语就应该是it或者是its sth,应该是类似of his day一个情况.
例句：His focus for much of his day is on work.

他一天大多数时候,注意力都放在他的工作上.
用of its day举例,My horse,Ben played in the garden yesterday.It run and jumped of its day.
我的马,名字叫做本,昨天在花园里玩.他那个时候（昨天）又是跑,又是跳的.